Hey Michel,
If you saw my site, you can obviously figure out that making my own stuff is a real fun hobby for me. The three usual sites for finding materials and harware are OWFinc.com, seattlefabrics.com, questoutfitters.com. OWF is the cheapest but their selection lacks... Its also the only one I use personally. Great customer service. The other two are used and liked as well. Seattle fabrics has probably got the most info about the materials. I don't mean to say it again but the backpacking.net site is full of people who make their own gear and is a wealth of info. As far as your arkels... Unless you want the chalange and pride of completely rebulding them, it is often cheaper and much less of a headache to buy new. But then again, you can't say I made these myself. Doesn't arkel have a lifetime guarrantee?
Good luck,
scott